Infrared Sensor Application Note 1-----------------Download：/en/.pdf

INFRARED GAS ABSORPTION SPECTRA
It is well known that many gas molecules can absorb radiation in the infrared portion of the electromagnetic spectrum. When infrared radiation is incident on the gas, the energy states of atoms vibrating in the molecules change in discrete steps when the wavelength of the infrared matches the molecules natural frequencies or resonances. Put simply, the vibrations of atoms held in their chemical bonds increase when excited by light of the right wavelength. A net absorption of infrared radiation effectively raises the gas temperature.